Chemical Injection Control System and Method for Controlling Chloramines

ABSTRACT

A method of automatically controlling chloramine concentration in a body of water contained in a reservoir includes: (a) determining residual chloramine concentration in a water sample; (b) automatically engaging a supply of chlorine to add chlorine when (i) the residual chloramine concentration in the water sample is determined to be below a predetermined residual chloramine concentration set-point or (ii) below a chloramine concentration percentage of a predetermined residual chloramine concentration set-point; (c) determining residual chloramine concentration in one or more additional water samples after step (b); (d) determining the rate of change in chloramine concentration; and (e) if the rate of change in chloramine concentration is below a set rate of change in chloramine concentration (i) automatically engaging a supply of ammonia and the supply of chlorine to add both ammonia and chlorine to the body of water, or (ii) stopping the supply of chlorine after step (d).

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/513,028, filed May 31, 2017, which is incorporatedherein by reference in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to chemical injection control systems forcontrolling chloramines and methods of operating such systems.

Description of Related Art

Water utilities typically add disinfectants to water systems to preventcontamination from germs and bacteria such as Salmonella. While chlorineis the most commonly used secondary disinfectant, many water utilitiesare turning to chloramines as an alternative. As compared to chlorine,chloramines have a longer residual life and are less prone todisinfection byproduct formation. Despite these advantages, chloramineusage can be problematic. For instance, a water system is typicallydosed with hypochlorite and ammonia to produce monochloramine; however,if the chlorine-to-ammonia ratio is not accurately controlled,undesirable side-effects occur such as nitrification, over-chlorination,and low oxidation levels. Thus, it is desirable to provide a chemicalinjection system that can be accurately controlled to continuouslyproduce stable forms of monochloramine in a water system at a desiredconcentration.

SUMMARY OF THE INVENTION

Generally, provided is an improved chloramine injection and controlsystem and method.

In one preferred and non-limiting embodiment or aspect, provided is amethod of automatically controlling chloramine concentration in a bodyof water contained in a reservoir. The method includes: (a) determiningresidual chloramine concentration in a water sample obtained from thebody of water; (b) automatically engaging a supply of chlorine to addchlorine to the body of water when (i) the residual chloramineconcentration in the water sample is determined to be below apredetermined residual chloramine concentration set-point or (ii) theresidual chloramine concentration in the water sample is determined tobe below a chloramine concentration percentage of a predeterminedresidual chloramine concentration set-point; (c) determining residualchloramine concentration in one or more additional water samplesobtained from the body of water after step (b); (d) determining the rateof change in chloramine concentration based on the residual chloramineconcentration obtained from at least two water samples of step (c) orbased on the residual chloramine concentration obtained from a watersample in step (c) and the water sample in step (a) if the residualchloramine concentration in the additional water samples is below thepredetermined residual chloramine concentration set-point or thechloramine concentration percentage of a predetermined residualchloramine concentration set-point; and (e) if the rate of change inchloramine concentration is below a set rate of change in chloramineconcentration (i) automatically engaging a supply of ammonia and thesupply of chlorine to add both ammonia and chlorine to the body ofwater, or (ii) stopping the supply of chlorine after step (d).

In another preferred and non-limiting embodiment or aspect, the supplyof chlorine is added to the body of water in step (b) when (i) theresidual chloramine concentration in the first water sample isdetermined to be below the predetermined residual chloramineconcentration set-point.

Further, in one preferred and non-limiting embodiment or aspect, thesupply of chlorine is added to the body of water in step (b) when (ii)the residual chloramine concentration in the first water sample isdetermined to be below the first chloramine concentration percentage ofthe predetermined residual chloramine concentration set-point.

In a preferred and non-limiting embodiment or aspect, the rate of changein chloramine concentration is determined by comparing the chloramineconcentration in at least one water sample of step a) or step c) withthe chloramine concentration in a subsequent water sample of step c)obtained after a set period of time.

In a preferred and non-limiting embodiment or aspect, the ammonia andchlorine are both added to the body of water in step e) when twoconsecutive determinations in the rate of change in chloramineconcentration are below the set rate of change in chloramineconcentration.

In a preferred and non-limiting embodiment or aspect, if the rate ofchange in chloramine concentration is determined to be at or above theset rate of change in chloramine concentration, the addition of chlorineonly to the body of water is maintained. Further, if the residualchloramine concentration in a water sample is determined to be at orabove the predetermined residual chloramine concentration set-point instep c), the supply of chlorine to the body of water is stopped. Inaddition, the supply of chlorine and the supply of ammonia are added tothe body of water during step e) until a subsequently obtained watersample is determined to be at or above the predetermined residualchloramine concentration set-point.

As indicated, a supply of chlorine can be added to the body of water ifthe residual chloramine concentration is determined to be below thechloramine concentration percentage of the predetermined residualchloramine concentration set-point. In certain preferred andnon-limiting embodiments or aspects, the chloramine concentrationpercentage is a percentage selected within a range of about 99% to about80% of the predetermined residual chloramine concentration set-point.

In certain preferred and non-limiting embodiments or aspects, if it isdetermined that the body of water has a residual chloramineconcentration at or above the predetermined residual chloramineconcentration set-point after step (b) or step (e), the method canfurther include: (f) determining residual chloramine concentration in asubsequent water sample obtained from the body of water; and (g)automatically engaging the supply of ammonia and the supply of chlorineto add both ammonia and chlorine to the body of water if (i) theresidual chloramine concentration in the subsequent water sample isdetermined to be below the predetermined residual chloramineconcentration set-point or (ii) the residual chloramine concentration inthe subsequent water sample is determined to be below the chloramineconcentration percentage of the predetermined residual chloramineconcentration set-point.

In any of the described steps, and in one preferred and non-limitingembodiment or aspect, the feed rate of at least one of the chlorine andammonia can be determined by reservoir water volume and dwell time.Further, when both chlorine and ammonia are added to the body of water,the chlorine and ammonia can be automatically added to provide a weightratio of chlorine to ammonia of 5:1. In addition, in some preferred andnon-limiting embodiments or aspects, determining the residual chloramineconcentration in the water samples includes measuring a total chlorineconcentration in the water samples.

In certain preferred and non-limiting embodiments or aspects, thechlorine and, optionally, the ammonia, are added to the body of water bya chemical dosing assembly that comprises chemical treatment flow tubesand a water motive tube. In such embodiments or aspects, the chlorineand, optionally, the ammonia, are added to the body of water by thechemical treatment flow tubes in an area above the water motive tube toform a high energy mixing zone.

In certain preferred and non-limiting embodiments or aspects, the methodfurther comprises re-starting the method at step a) after apredetermined period of time when the supply of chlorine is stoppedafter step d).

In one preferred and non-limiting embodiment or aspect, provided is atreatment delivery system for automatically controlling chloramineconcentration in a body of water contained in a reservoir. The systemincludes: a chemical dosing assembly at least partially submerged in thebody of water; a water sampling assembly configured to extract watersamples from the body of water at different points in time; an analyzerin fluid communication with the water sampling assembly and configuredto determine residual chloramine concentration in the water samples; acontroller in operable communication with the analyzer; and one or morecomputer-readable storage mediums in operable communication with thecontroller and containing programming instructions that, when executed,cause the controller to: (a) determine whether the residual chloramineconcentration in the water sample obtained from the body of water isbelow a predetermined residual chloramine concentration set-point orbelow a chloramine concentration percentage of a predetermined residualchloramine concentration set-point; (b) engage the chemical dosingassembly to add chlorine to the body of water when (i) the residualchloramine concentration in the water sample is determined to be below apredetermined residual chloramine concentration set-point or (ii) theresidual chloramine concentration in the water sample is determined tobe below the chloramine concentration percentage of a predeterminedresidual chloramine concentration set-point; (c) determine residualchloramine concentration in one or more additional water samplesobtained from the body of water after step (b); (d) determine the rateof change in chloramine concentration based on the residual chloramineconcentration obtained from at least two water samples of step (c) orbased on the residual chloramine concentration obtained from a watersample in step (c) and the water sample in step (a) if the residualchloramine concentration in the additional water samples is below thepredetermined residual chloramine concentration set-point or thechloramine concentration percentage of a predetermined residualchloramine concentration set-point; and (e) if the rate of change inchloramine concentration is below a set rate of change in chloramineconcentration (i) automatically engage a supply of ammonia and thesupply of chlorine to add both ammonia and chlorine to the body ofwater, or (ii) stop the supply of chlorine after step (d).

In some preferred and non-limiting embodiments or aspects, the watersampling assembly is a component of the chemical dosing assembly, andthe analyzer is a total chlorine analyzer. Further, the chemical dosingassembly can also include a water motive tube positioned below a releasepoint of at least one chemical treatment flow tube. The chemical dosingassembly can further include a second chemical treatment flow tube withthe water motive tube positioned below a release point of the secondchemical treatment flow tube.

In certain preferred and non-limiting embodiments or aspects, the firstand second chemical treatment flow tubes are configured to deliver thechlorine and, optionally, the ammonia, to an area above a release pointof the water motive tube to form a high energy mixing zone.

In addition, and in one preferred and non-limiting embodiment or aspect,the system can include a hypochlorite storage tank, an ammonia storagetank, or both a hypochlorite storage tank and an ammonia storage tank.In some preferred and non-limiting embodiments or aspects, the systemincludes a hypochlorite generation system. The controller can also beprogrammed to provide a weight ratio of chlorine to ammonia of 5:1.

Additional preferred and non-limiting embodiments or aspects are setforth and described in the following clauses.

Clause 1. A method of automatically controlling chloramine concentrationin a body of water contained in a reservoir, the method comprising: (a)determining residual chloramine concentration in a water sample obtainedfrom the body of water; (b) automatically engaging a supply of chlorineto add chlorine to the body of water when: (i) the residual chloramineconcentration in the water sample is determined to be below apredetermined residual chloramine concentration set-point; or (ii) theresidual chloramine concentration in the water sample is determined tobe below a chloramine concentration percentage of a predeterminedresidual chloramine concentration set-point; (c) determining residualchloramine concentration in one or more additional water samplesobtained from the body of water after step (b); (d) determining the rateof change in chloramine concentration based on the residual chloramineconcentration obtained from at least two water samples of step (c) orbased on the residual chloramine concentration obtained from a watersample in step (c) and the water sample in step (a) if the residualchloramine concentration in the additional water samples is below thepredetermined residual chloramine concentration set-point or thechloramine concentration percentage of a predetermined residualchloramine concentration set-point; and (e) if the rate of change inchloramine concentration is below a set rate of change in chloramineconcentration (i) automatically engaging a supply of ammonia and thesupply of chlorine to add both ammonia and chlorine to the body ofwater, or (ii) stopping the supply of chlorine after step (d).

Clause 2. The method of clause 1, wherein the supply of chlorine isadded to the body of water in step (b) when (i) the residual chloramineconcentration in the water sample of step (a) is determined to be belowthe predetermined residual chloramine concentration set-point.

Clause 3. The method of clause 1 or 2, wherein the supply of chlorine isadded to the body of water in step (b) when (ii) the residual chloramineconcentration in the water sample of step (a) is determined to be belowthe chloramine concentration percentage of the predetermined residualchloramine concentration set-point.

Clause 4. The method of any of clauses 1-3, wherein the rate of changein chloramine concentration is determined by comparing the chloramineconcentration in at least one water sample of step (a) or step (c) withthe chloramine concentration in a subsequent water sample of step (c)obtained after a set period of time.

Clause 5. The method of any of clauses 1-4, wherein the ammonia andchlorine are both added to the body of water in step (e) when twoconsecutive determinations in the rate of change in chloramineconcentration are below the set rate of change in chloramineconcentration.

Clause 6. The method of any of clauses 1-5, wherein, if the rate ofchange in chloramine concentration is determined to be at or above theset rate of change in chloramine concentration, the addition of chlorineonly to the body of water is maintained.

Clause 7. The method of any of clauses 1-6, wherein, if the residualchloramine concentration in a water sample is determined to be at orabove the predetermined residual chloramine concentration set-point instep (c), the supply of chlorine to the body of water is stopped.

Clause 8. The method of any of clauses 1-7, wherein the supply ofchlorine and the supply of ammonia are added to the body of water duringstep (e) until a subsequently obtained water sample is determined to beat or above the predetermined residual chloramine concentrationset-point.

Clause 9. The method of any of clauses 1-8, wherein the chloramineconcentration percentage is a percentage selected within a range ofabout 99% to about 80% of the predetermined residual chloramineconcentration set-point.

Clause 10. The method of any of clauses 1-9, wherein a feed rate of atleast one of the chlorine and ammonia are determined by reservoir watervolume and dwell time.

Clause 11. The method of any of clauses 1-10, wherein, if it isdetermined that the body of water has a residual chloramineconcentration at or above the predetermined residual chloramineconcentration set-point after step (b) or step (e), the method furthercomprises: (f) determining residual chloramine concentration in asubsequent water sample obtained from the body of water; and (g)automatically engaging the supply of ammonia and the supply of chlorineto add both ammonia and chlorine to the body of water if: (i) theresidual chloramine concentration in the subsequent water sample isdetermined to be below the predetermined residual chloramineconcentration set-point; or (ii) the residual chloramine concentrationin the subsequent water sample is determined to be below the chloramineconcentration percentage of the predetermined residual chloramineconcentration set-point.

Clause 12. The method of any of clauses 1-11, wherein determining theresidual chloramine concentration in the water samples comprisesmeasuring a total chlorine concentration in the water samples.

Clause 13. The method of any of clauses 1-12, wherein the chlorine andammonia are both automatically added to the body of water to provide aweight ratio of chlorine to ammonia of 5:1.

Clause 14. The method of any of clauses 1-13, wherein the chlorine and,optionally, the ammonia, are added to the body of water by a chemicaldosing assembly that comprises chemical treatment flow tubes and a watermotive tube, and wherein the chlorine and, optionally, the ammonia, areadded to the body of water by the chemical treatment flow tubes in anarea above the water motive tube to form a high energy mixing zone.

Clause 15. The method of any of clauses 1-14, further comprisingre-starting the method at step a) after a predetermined period of timewhen the supply of chlorine is stopped after step d).

Clause 16: A treatment delivery system for automatically controllingchloramine concentration in a body of water contained in a reservoircomprising: a chemical dosing assembly at least partially submerged inthe body of water; a water sampling assembly configured to extract watersamples from the body of water at different points in time; an analyzerin fluid communication with the water sampling assembly and configuredto determine residual chloramine concentration in the water samples; acontroller in operable communication with the analyzer; and one or morecomputer-readable storage mediums in operable communication with thecontroller and containing programming instructions that, when executed,cause the controller to: (a) determine residual chloramine concentrationin a water sample obtained from the body of water; (b) automaticallyengage a supply of chlorine to add chlorine to the body of water when:(i) the residual chloramine concentration in the water sample isdetermined to be below a predetermined residual chloramine concentrationset-point; or (ii) the residual chloramine concentration in the watersample is determined to be below a chloramine concentration percentageof a predetermined residual chloramine concentration set-point; (c)determine residual chloramine concentration in one or more additionalwater samples obtained from the body of water after step (b); (d)determine the rate of change in chloramine concentration based on theresidual chloramine concentration obtained from at least two watersamples of step (c) or based on the residual chloramine concentrationobtained from a water sample in step (c) and the water sample in step(a) if the residual chloramine concentration in the additional watersamples is below the predetermined residual chloramine concentrationset-point or the chloramine concentration percentage of a predeterminedresidual chloramine concentration set-point; and (e) if the rate ofchange in chloramine concentration is below a set rate of change inchloramine concentration (i) automatically engage a supply of ammoniaand the supply of chlorine to add both ammonia and chlorine to the bodyof water, or (ii) stop the supply of chlorine after step (d).

Clause 17. The system of clause 16, wherein the water sampling assemblyis a component of the chemical dosing assembly.

Clause 18. The system of clauses 16 or 17, wherein the analyzercomprises a total chlorine analyzer.

Clause 19. The system of any of clauses 16-18, wherein the chemicaldosing assembly further comprises a water motive tube positioned below arelease point of at least one chemical treatment flow tube.

Clause 20. The system of any of clauses 16-19, wherein the chemicaldosing assembly further comprises a second chemical treatment flow tubeand, wherein the water motive tube is positioned below a release pointof the second chemical treatment flow tube.

Clause 21. The system of any of clauses 16-20, wherein the first andsecond chemical treatment flow tubes are configured to deliver thechlorine and, optionally, the ammonia, to an area above a release pointof the water motive tube to form a high energy mixing zone.

Clause 22: The system of any of clauses 16-21, further comprising ahypochlorite storage tank, an ammonia storage tank, or both ahypochlorite storage tank and an ammonia storage tank.

Clause 23: The system of any of clauses 16-22, further comprising ahypochlorite generation system.

Clause 24: The system of any of clauses 16-23, wherein the controller isprogrammed to provide chlorine and ammonia at a weight ratio of chlorineto ammonia of 5:1.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a treatment delivery system according to theprinciples of the present invention;

FIG. 2 illustrates a chemical dosing assembly according to theprinciples of the present invention;

FIG. 3 is a chloramine breakpoint curve;

FIG. 4 are graphs illustrating the addition of chlorine in the presenceof free ammonia to generate chloramine;

FIG. 5 are graphs illustrating the addition of chlorine and ammonia inthe absence of free ammonia to generate chloramine;

FIG. 6 is a graph of the residual chloramine concentration and rate ofchange of chloramine concentration using a process according to theprinciples of the present invention; and

FIG. 7 is a graph of the residual chloramine concentration and rate ofchange of chloramine concentration using a process according to theprinciples of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

For purposes of the following detailed description, it is to beunderstood that the invention may assume various alternative variationsand step sequences, except where expressly specified to the contrary.Moreover, other than in any operating examples, or where otherwiseindicated, all numbers expressing, for example, quantities ofingredients used in the specification and claims are to be understood asbeing modified in all instances by the term “about”. Accordingly, unlessindicated to the contrary, the numerical parameters set forth in thefollowing specification and attached claims are approximations that mayvary depending upon the desired properties to be obtained by the presentinvention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard variation found in theirrespective testing measurements.

Also, it should be understood that any numerical range recited herein isintended to include all sub-ranges subsumed therein. For example, arange of “1 to 10” is intended to include all sub-ranges between (andincluding) the recited minimum value of 1 and the recited maximum valueof 10, that is, having a minimum value equal to or greater than 1 and amaximum value of equal to or less than 10.

Further, the terms “upper,” “lower,” “right,” “left,” “vertical,”“horizontal,” “top,” “bottom,” “lateral,” “longitudinal,” andderivatives thereof shall relate to the invention as it is oriented inthe drawing figures. However, it is to be understood that the inventionmay assume alternative variations and step sequences, except whereexpressly specified to the contrary. It is also to be understood thatthe specific devices and processes illustrated in the attached drawings,and described in the specification, are simply exemplary embodiments ofthe invention. Hence, specific dimensions and other physicalcharacteristics related to the embodiments disclosed herein are not tobe considered as limiting.

In this application, the use of the singular includes the plural andplural encompasses singular, unless specifically stated otherwise. Inaddition, in this application, the use of “or” means “and/or” unlessspecifically stated otherwise, even though “and/or” may be explicitlyused in certain instances.

Referring to FIG. 1, and in one preferred and non-limiting embodiment oraspect, the present invention is directed to a treatment delivery system10 that can be used to automatically control chloramine concentration ina body of water 12 contained in a reservoir 14. The term “automaticcontrol” refers to the absence of substantial participation of a humanoperator in normal operations manually controlling the controllablecomponents. As such, the treatment delivery system 10 can be controlledwithout an operator monitoring or adjusting the various parameters ofthe treatment delivery system 10 during normal operations.

As shown in FIG. 1, the treatment delivery system 10 can include achemical dosing assembly 16 that can be at least partially submerged inthe body of water 12. Referring to FIG. 2, and in one preferred andnon-limiting embodiment or aspect, the chemical dosing assembly 16 caninclude a water motive tube 20, a first chemical treatment flow tube 22,and, optionally, a second chemical treatment flow tube 24. The watermotive tube 20 and chemical treatment flow tubes 22, 24 of the chemicaldosing assembly 16 can be oriented to expel water and chemicals,respectively, into the body of water 12 held in the reservoir 14. Thechemicals used with the chemical treatment tubes 22, 24 can be selectedto form chloramine, such as monochloramine, when expelled into a jet ofwater expelled from the water motive tube 20. For example, the firstchemical treatment flow tube 22 can be in fluid communication with asource of chlorine and can be configured to expel chlorine into the bodyof water 12 while the second chemical treatment flow tube 24 can be influid communication with a source of ammonia and can be configured toexpel ammonia into the body of water 12. Because of the configuration ofthe nozzle ends of the first and second chemical treatment flow tubes22, 24, the chemicals expelled through the ends thereof come into almostimmediate contact with one another and can begin reacting soon afterbeing expelled into the body of water 12.

In addition, and in one preferred and non-limiting embodiment or aspect,the water motive tube 20 is positioned below the release point of thefirst and second chemical treatment flow tubes 22, 24 to circulate thechemicals into the body of water 12. The flow of water out of the watermotive tube 20 can also create a high energy, high velocity mixing zonedirectly above the water motive tube 20 where the chemicals can bereleased, which helps the chemicals interact and form a particularcompound, such as monochloramine. The treatment delivery system 10 caninclude multiple chemical dosing assemblies 16 strategically locatedthroughout the reservoir 14.

The treatment delivery system 10 can further include a water samplingassembly 26 that is configured to obtain or extract water samples fromthe body of water 12 at different points in time, such as continuously,periodically, and/or according to a pre-programmed cycle. As shown inFIG. 2, the water sampling line 26 can be a component of the chemicaldosing assembly 16. For example, the water motive tube 20, chemicaltreatment tubes 22, 24, and water sampling assembly 26 of the chemicaldosing assembly 16 can be secured to a frame 27 that is adapted to restat the bottom of the reservoir 14. Alternatively, the water motive tube20, the chemical treatment tubes 22, 24, and the water sampling assembly26 can extend into the reservoir 14 to a desired depth. Yet anotheralternative (not shown) is that the water sampling assembly 26 can beseparate from the chemical dosing assembly 16 and may be located at anylocation within the reservoir 14. Treatment delivery system 10 may alsoinclude multiple water sampling assemblies 26 positioned throughout thereservoir 14.

Referring to FIG. 1, and in one preferred and non-limiting embodiment oraspect, the treatment delivery system 10 can also include an analyzer 30that is in fluid communication with the water sampling assembly 26. Theanalyzer 30 is configured to receive the water samples and analyze thecontents thereof. In one preferred and non-limiting embodiment oraspect, the analyzer 30 is programmed or configured to determine theconcentration of chloramine in the water sample. Various methods areknown to determine the chloramine concentration in a sample of water. Inone preferred and non-limiting embodiment or aspect, the analyzer 30 is,or includes, a chloramine analyzer, such as the APA 6000 Ammonia andMonochloramine Analyzer commercially available from Hach Company ofLoveland, Colo., which can directly measure the chloramine concentrationin the water sample. In another preferred and non-limiting embodiment oraspect, the analyzer 30 is, or includes, a total chlorine analyzer, suchas the total chlorine analyzer commercially available from ProMinentFluid Controls, Inc. of Pittsburgh, Pa., which can be used to indirectlymeasure the chloramine concentration. In this latter embodiment, theanalyzer 30 measures the total chlorine residual in a water sample and,from this measurement, the residual chloramine concentration isdetermined either by the analyzer 30 or by a controller 40 or otherprocessor associated therewith. It will be appreciated that the analyzer30 may be a standalone device or, in other embodiments, may be softwareand/or firmware executed by the controller 40 or other processor.

As indicated, the treatment delivery system 10 can further include acontroller 40 that is in operable communication with the analyzer 30 sothat measurements and other data gathered, and/or determined by theanalyzer 30, can be transferred or accessed by the controller 40. One ormore computer-readable storage mediums can be in operable communicationwith the controller 40. The computer-readable storage mediums cancontain programming instructions that, when executed, cause thecontroller 40 to perform multiple tasks. This includes programmingalgorithms such as those described herein that allow the controller 40to control the administration of chlorine and/or ammonia into the bodyof water 12 for establishing, reestablishing, and maintaining targetresidual chloramine levels within the body of water 12. The programminginstructions can be updated and modified. For example, the targetresidual chloramine level can be changed as can the flow rates of thechlorine and/or ammonia and the water sampling frequency.

In one example, and in one preferred and non-limiting embodiment oraspect, the programming instructions, when executed, can cause thecontroller 40 to: measure and/or analyze a first water sample obtainedfrom the body of water 12, and/or determine whether the residualchloramine concentration in the first water sample is below apre-determined residual chloramine concentration set-point or below afirst chloramine concentration percentage of a pre-determined residualchloramine concentration set-point; engage (or control) the chemicaldosing assembly 16 to add chlorine to the body of water 12 if theresidual chloramine concentration in the first water sample isdetermined to be below the residual chloramine concentration set-pointor below the first chloramine concentration percentage of the residualchloramine concentration set-point; measure and/or analyze additionalwater samples obtained from the body of water 12 after chlorine isadded, and/or determine the rate of change in chloramine concentrationbased on the residual chloramine concentration obtained from at leasttwo water samples; and engage (or control) the chemical dosing assembly16 to add ammonia and chlorine to the body of water 12 if the rate ofchange in chloramine concentration is below a set rate of change inchloramine concentration. It will be appreciated that controller 40 mayinclude one or more microprocessors, CPUs, and/or other computingdevices.

As further shown in FIG. 1, and in one preferred and non-limitingembodiment or aspect, treatment delivery system 10 can include multiplechemical storage tanks, such as a first chemical storage tank 200 and asecond chemical storage tank 300, which are configured to transportchemicals to the chemical dosing assembly 16 via one or more meteringpumps. As indicated, the treatment delivery system 10 can deliver asource of chlorine and a source of ammonia into the body of water 12. Assuch, the chemical storage tanks 200, 300 can store a source of chlorineand a source of ammonia. Because the treatment delivery system 10 iscapable of delivering any type of chlorine and ammonia source, thechemical storage tanks 200, 300 can be selected to store various sourcesof chlorine and ammonia. Non-limiting examples of chlorine sources thatcan be used with the present invention include pressurized chlorine gasand hypochlorites such as sodium hypochlorite, potassium hypochlorite,and calcium hypochlorite. Non-limiting examples of ammonia sources thatcan be used with the present invention include pressurized anhydrousammonia, aqueous ammonia, and liquid ammonium sulfate. The chemicalstorage tanks 200, 300 can also be supplied by on-site chemicalgeneration systems, such as an on-site hypochlorite generation system400 as shown in FIG. 1 for example that can generate hypochlorite basedchemicals (e.g., sodium hypochlorite or potassium hypochlorite) directlyat the water treatment site.

Non-limiting examples of chemical dosing assemblies, chemical generationsystems, and the like are disclosed in U.S. Pat. No. 9,039,902, which isincorporated by reference herein in its entirety. In particular, U.S.Pat. No. 9,039,902 describes chemical dosing assemblies, as well as ahypochlorite generation system, that can be used as the source ofchlorine that is present in first chemical storage tank 200 and,ultimately, supplied to the body of water 12. The treatment deliverysystem 10 can also utilize other mixing systems as well. For example,the treatment delivery system 10 can also utilize the mixing systemdisclosed in U.S. Pat. No. 7,862,302, which is incorporated by referenceherein in its entirety.

As indicated, the treatment delivery system 10, previously described,can be used for automatically controlling chloramine concentration in abody of water 12 contained in a reservoir 14. As such, the presentinvention is also directed to a method of automatically controllingchloramine concentration in a body of water 12 contained in a reservoir14. The method can be implemented through one or more algorithms andcontrols contained in programming instructions that, when executed,cause the system 10 to take certain actions, as described below.

The method can first include measuring, analyzing, and/or determiningthe residual chloramine concentration in a water sample obtained fromthe body of water 12. The water sample can be obtained with the watersampling assembly 26 and transported to the analyzer 30 that is in fluidcommunication with the water sampling assembly 26. The analyzer 30 canthen measure, analyze, and/or determine the residual chloramineconcentration. The determination of the residual chloramineconcentration can include measuring the residual total chlorineconcentration in the water sample.

The residual chloramine concentration determination can be reported to acontroller 40 that is in operable communication with one or morecomputer-readable storage mediums. The controller 40 also has knowledgeof, or access to, information about the set-point (target) residualchloramine concentration. If the residual chloramine concentration inthe water sample is determined to be below the residual chloramineconcentration set-point (which can be based on a residual total chlorineconcentration set-point, for example), then the programming instructionsof the computer-readable storage mediums will cause the controller 40 toautomatically engage (or control) a supply of chlorine to add chlorineto the body of water 12. The chlorine can be distributed into the bodyof water 12 through treatment tube 22 and/or 24 of the chemical dosingassembly 16.

In some preferred and non-limiting embodiments or aspects, thepreviously described method step of adding chlorine into the body ofwater 12 is controlled by the following algorithm I: y<x=add chlorine,where “y” is the residual chloramine concentration determined in thewater sample and “x” is the residual chloramine concentration set-point.Thus, the programming instructions can include algorithm I that, whensatisfied, will cause the controller 40 to automatically engage (orcontrol) a supply of chlorine to add chlorine to the body of water 12.

After adding chlorine, additional samples of water can be obtained fromthe body of water 12 with the water sampling assembly 26. The analyzer30 can again measure, analyze, and/or determine the residual chloramineconcentration in one or more (but at least one) additional subsequentwater samples. The residual chloramine concentration determination inthe subsequent sample(s) can be sent to the controller 40 in operablecommunication with the computer-readable storage mediums. If, after thepassage of a length of time, the residual chloramine concentration in anadditional water sample is determined to be below the residualchloramine concentration set-point, a rate of change in the chloramineconcentration can be determined by the controller with the programminginstructions. As used herein, the “rate of change in the chloramineconcentration” refers to the change in the chloramine concentrationvalue over time based on the chloramine concentration in two or morewater samples.

The previously described rate of change in the chloramine concentrationis determined by the following formula: rate of change=[subsequentlydetermined chloramine concentration value/a previously determinedchloramine concentration value]−1. Thus, the programming instructionscan include the rate of change formula to allow the controller 40 todetermine the rate of change in chloramine concentration over time inthe body of water 12.

In some preferred and non-limiting embodiments or aspects, the rate ofchange in chloramine concentration is determined with the chloramineconcentration in the water sample used to determine if chlorine shouldbe added to the body of water 12 and the chloramine concentration in asubsequently obtained water sample. Alternatively, the rate of change inchloramine concentration is determined with the chloramine concentrationin two subsequent additional water samples obtained after initiating theaddition of chlorine to the body of water 12.

In some preferred and non-limiting embodiments or aspects, the rate ofchange in chloramine concentration is determined by comparing thechloramine concentration in two water samples obtained after a setperiod of time. For instance, the rate of change in chloramineconcentration can be based on the chloramine concentration in a firstwater sample and the chloramine concentration in a subsequent watersample obtained after a specified period of time, such as 10 minutes or30 minutes or one hour for example, after determining the chloramineconcentration in the first water sample.

After determining the rate of change in chloramine concentration,ammonia and chlorine are both added to the body of water 12 if the rateof change in chloramine concentration is below a set rate of change inchloramine concentration. As used herein, a “set rate of change inchloramine concentration” refers to a predetermined (target) increase ordecrease in the rate of change in chloramine concentration. For example,the set rate of change in chloramine concentration can be 0.02 mg/L/hourand if the rate of change in residual chloramine concentration isdetermined to be below 0.02 mg/L/hour, the programming instructions willcause the controller 40 to automatically engage (or control) a supply ofchlorine and ammonia to add both ammonia and chlorine to the body ofwater 12. The chlorine and ammonia can be added to the body of water 12through treatment tubes 22 and 24 of the chemical dosing assembly 16.

In some preferred and non-limiting embodiments or aspects, thepreviously described method step of adding both chlorine and ammoniainto the body of water 12 is controlled by the following algorithm II:w<y=add both chlorine and ammonia, where “w” is the rate of change inchloramine concentration determined in from the water samples and “y” isthe set rate of change in chloramine concentration. Thus, theprogramming instructions can include algorithm II that, when satisfied,will cause the controller 40 to automatically engage (or control) asupply of chlorine and a supply of ammonia to add both chlorine andammonia to the body of water 12.

In some preferred and non-limiting embodiments or aspects, ammonia andchlorine are both added to the body of water 12 when two consecutivedeterminations in the rate of change in chloramine concentration arebelow the set rate of change in chloramine concentration. For example,the set rate of change in chloramine concentration can be 0.02 mg/L/hourand if two consecutive determinations in the rate of change in residualchloramine concentration is determined to be below 0.02 mg/L/hour, theprogramming instructions will cause the controller 40 to automaticallyengage (or control) a supply of chlorine and ammonia to add both ammoniaand chlorine to the body of water 12.

It is appreciated that the two consecutive determinations in the rate ofchange in residual chloramine concentration can be obtained over aspecified period of time. For instance, a first determination in therate of change in residual chloramine concentration can be determinedfollowed by a second determination in the rate of change in residualchloramine concentration after a specified period of time, such as 10minutes or 30 minutes or one hour for example, after obtaining the firstdetermination in the rate of change. If the first and second rate ofchange in chloramine concentration is below the set rate of change inchloramine concentration the programming instructions will cause thecontroller 40 to automatically engage (or control) a supply of chlorineand ammonia to add both ammonia and chlorine to the body of water 12.

Chlorine and ammonia are added to the body of water 12 until asubsequently obtained water sample is determined to be at or above theresidual chloramine concentration set-point, at which point theprogramming instructions will cause the controller 40 to stop the supplyof chlorine and the supply of ammonia into the body of water 12.

In some preferred and non-limiting embodiments or aspects, thepreviously described method step of stopping the addition of chlorineand ammonia into the body of water 12 is controlled by the followingalgorithm III: z≥x=stop the supply of chlorine and ammonia, where “z” isthe residual chloramine concentration determined in a subsequent watersample as chlorine and ammonia are being supplied to the body of water12, and “x” is the residual chloramine concentration set-point. Thus,the programming instructions can include algorithm III that, whensatisfied, will cause the controller 40 to stop automatically engaging(or controlling) a supply of chlorine and a supply of ammonia, andtherefore, stop adding chlorine and ammonia to the body of water 12.

Alternatively, if the residual chloramine concentration in theadditional water samples is determined to be at or above the set rate ofchange in chloramine concentration in the first water sample, but belowthe residual chloramine concentration set-point, the programminginstructions will cause the controller 40 to continue to automaticallyengage (or control) a supply of chlorine to add chlorine only to thebody of water 12.

In some preferred and non-limiting embodiments or aspects, the methodstep of continually adding chlorine is controlled by the followingalgorithm IV: w≥y and w′<x=add chlorine, where “w” is the rate of changein chloramine concentration determined in an additional subsequent watersample, “y” is the set rate of change in chloramine concentration, w′ isthe residual chloramine concentration determined in a subsequent watersample, and “x” is the residual chloramine concentration set-point.Thus, the programming instructions can include algorithm IV that, whensatisfied, will cause the controller 40 to continue to automaticallyengage (or control) a supply of chlorine to add chlorine to the body ofwater 12.

Further, if the residual chloramine concentration in a subsequentadditional water sample is determined to be at or above the residualchloramine concentration set-point, the programming instructions willcause the controller 40 to stop the supply of chlorine into the body ofwater 12.

In some preferred and non-limiting embodiments or aspects, the methodstep of stopping the supply of chlorine is controlled by the followingalgorithm V: w≥x=stop the supply of chlorine, where “w” is the residualchloramine concentration determined in the second water sample, and “x”is the residual chloramine concentration set-point. Thus, theprogramming instructions can include algorithm V that, when satisfied,will cause the controller 40 to stop automatically engaging (orcontrolling) a supply of chlorine, and therefore, stop adding chlorineto the body of water 12.

In some preferred and non-limiting embodiments or aspects, thecontroller 40 is programmed to stop the supply of chlorine or the supplyof chlorine and ammonia into the body of water 12 when the residualchloramine concentration is above a particular percentage of theresidual chloramine concentration set-point. For example, the controller40 can be programmed to stop the supply of chlorine or the supply ofchlorine and ammonia into the body of water 12 when the residualchloramine concentration in a water sample is a percentage selectedwithin a range of 101% to 110% of the residual chloramine concentrationset-point, or a percentage selected within a range of 101% to 105% ofthe residual chloramine concentration set-point.

In such preferred and non-limiting embodiments or aspects, differentprogramming algorithms are used to control when the supply of chlorineand/or the supply of chlorine and ammonia into the body of water 12 isstopped. For instance, the method step of stopping the supply ofchlorine can be controlled by the following algorithm VI:w>[(t)(x)]=stop the supply of chlorine, where “w” is the residualchloramine concentration determined in the second water sample, “t” is apercentage selected within a range of 101% to 110%, and “x” is theresidual chloramine concentration set-point.

In addition, the method step of stopping the addition of chlorine andammonia into the body of water 12 can be controlled by the followingalgorithm VII: z>[(t)(x)]=stop the supply of chlorine and ammonia, where“z” is the residual chloramine concentration determined in a subsequentwater sample as chlorine and ammonia are being supplied to the body ofwater 12, “t” is a percentage selected within a range of 101% to 110%,and “x” is the residual chloramine concentration set-point. Thus, theprogramming instructions can include, or can be modified to include,algorithms VI and/or VII that, when satisfied, will cause the controller40 to stop automatically engaging (or controlling) a supply of chlorineand/or a supply of chlorine and a supply of ammonia.

In some non-limiting embodiments, the supply of chlorine is stoppedafter determining the rate of change in chloramine concentration. Forexample, the supply of chlorine can be stopped in such embodimentsbecause ammonia is not available or the system is only being used totie-up free ammonia. When the supply of chlorine is stopped afterdetermining the rate of change in chloramine concentration, the processdescribed herein will re-start after a predetermined period of time.

It is appreciated that the previously described method works inaccordance with the chloramine breakpoint curve, shown in FIG. 3. Inparticular, the previously described steps are used to achieve andmaintain an ideal state of monochloramine disinfectant by predictingwhere the chloramine concentration in the body of water 12 resides alongthe breakpoint curve, the rate at which chloramine concentration isincreasing and decreasing in the body of water 12 over time, andadjusting the input of chlorine or chlorine and ammonia into the body ofwater 12 to achieve and maintain a position at or near the ideal state.As shown in FIG. 3, the ideal state (i.e., the maximum monochloramineconcentration obtainable in a body of water 12) is typically achieved ata weight ratio of chlorine (Cl₂) to ammonia-nitrogen (NH₃—N) of 5:1.

Referring to FIGS. 4 and 5, and in one preferred and non-limitingembodiment or aspect, the method includes at least two modes, or stages,in view of the chloramine breakpoint curve. In the first mode shown inFIG. 4, it is assumed that free ammonia is present in the body of water12. During the first mode, water samples are periodically drawn from thebody of water 12 and analyzed to determine the chloramine concentration.In one preferred and non-limiting embodiment or aspect, thisdetermination is accomplished by measuring the total chlorine present inthe sample using a total chlorine analyzer, such as the total chlorineanalyzer commercially available from ProMinent Fluid Controls, Inc. ofPittsburgh, Pa. If the system 10 determines that the total chlorinelevels measured are in decline, the controller 40 is configured toengage (or control) the treatment tubes 22 or 24 to add chlorine to thebody of water 12. Because free ammonia is assumed to be present, newlyadded chlorine will react with the free ammonia to generate chloramine,thus increasing the concentration of chloramine in the body of water 12and reducing the concentration of free ammonia, as reflected in FIG. 4.Once the residual chloramine concentration set-point is reestablished,or established in the first instance, the addition of chlorine cancease.

In the second mode or stage of the control method as shown in FIG. 5, nofree ammonia is present in the body of water 12. Because no free ammoniais present, the addition of chlorine in response to a recognized drop inthe chloramine concentration will result not in an upswing (or increase)in the chloramine concentration, as in the first mode described above,but rather in a further reduction in the chloramine concentration. Thisis caused by the absence of free ammonia in the body of water 12, whichprecludes the formation of chloramine through a reaction between theadded chlorine and free ammonia. If, after the addition of chlorine inthe first mode, the chloramine concentration does not increase after asufficient amount of time and the rate of change in the chloramineconcentration is below the set rate of change in chloramineconcentration, the system 10 can conclude that free ammonia is absentfrom the body of water 12. In response, the controller 40 is configuredto engage (or control) a source of chlorine and a source of ammonia toinject into the body of water 12, as reflected in FIG. 5. The ammoniaand chlorine can continue being added until analysis of water samplesextracted from the body of water 12 determines that the residualchloramine concentration set-point has been reestablished (orestablished).

It is appreciated that the second mode is initiated by the ability ofthe system 10 to predict the location of the chloramine reaction on thebreak point curve and the rate at which the chloramine concentration isincreasing or decreasing. For instance, if the measured total chlorineresidual concentration continues to decrease as chlorine is added, whichin turn results in a negative rate of change in chloramineconcentration, the system 10 can conclude that no free ammonia ispresent and that the residual chloramine concentration is decreasingpast the ideal state shown in FIG. 5. As a result, the second mode isinitiated and the controller 40 will add chlorine and ammonia into thebody of water 12.

In certain preferred and non-limiting embodiments or aspects, the methoduses a chloramine concentration percentage to determine when to engage(or control) and add a supply of chlorine to the body of water 12. Forinstance, the programming instructions can cause the controller 40 toengage (or control) a supply of chlorine and add the chlorine to thebody of water 12 when it is determined that the residual chloramineconcentration in a water sample is below a percentage selected within arange of 99% to 80% of the residual chloramine concentration set-point,or below a percentage selected within a range of 99% to 85% of theresidual chloramine concentration set-point, or below a percentageselected within a range of 99% to 90% of the residual chloramineconcentration set-point, or below a percentage selected within a rangeof 99% to 95% of the residual chloramine concentration set-point.

In some preferred and non-limiting embodiments or aspects, thepreviously described method step of adding chlorine into the body ofwater 12 based on a chloramine concentration percentage is controlled bythe following algorithm VIII: y<[(a)(x)]=add chlorine, where “y” is theresidual chloramine concentration determined in the first water sample,“a” is a percentage selected within a range of 99% to 80%, and “x” isthe residual chloramine concentration set-point. Thus, the programminginstructions can include, or can be modified to include, algorithm VIIIthat, when satisfied, will cause the controller 40 to automaticallyengage (or control) a supply of chlorine to add chlorine to the body ofwater 12.

In one preferred and non-limiting embodiment or aspect, the residualchloramine concentration set-point is 2.5 mg/L and the controller 40 isprogrammed to engage (or control) a supply of chlorine and add thechlorine to the body of water 12 when it is determined that the residualchloramine concentration in a water sample is below 95% of the residualchloramine concentration set-point. As a result, the controller 40 willengage (or control) a supply of chlorine and add the chlorine to thebody of water 12 only when the residual chloramine concentration in awater sample is below a residual chloramine concentration of 2.375 mg/L.Thus, the method can be programmed to add chlorine to the body of water12 when it is determined that the residual chloramine concentration isbelow a selected percentage of the residual chloramine concentrationset-point.

As chlorine is supplied to the body of water 12 in response to a firstwater sample being below a certain percentage of the residual chloramineconcentration set-point, a subsequent water sample is obtained andanalyzed to determine the new residual chloramine concentration and therate of change in chloramine concentration based on the new andpreviously determined residual chloramine concentration. If the rate ofchange in chloramine concentration is determined to be below the setrate of change in chloramine concentration, the programming instructionswill cause the controller 40 to automatically engage (or control) asupply of chlorine and ammonia to add both ammonia and chlorine to thebody of water 12. For example, in some preferred and non-limitingembodiments or aspects, the programming instructions also utilizealgorithm II that, when satisfied, causes the controller 40 toautomatically engage (or control) a supply of chlorine and a supply ofammonia to add both chlorine and ammonia to the body of water 12.

As previously described, chlorine and ammonia are added to the body ofwater 12 until a subsequently obtained water sample is determined to beat or above the residual chloramine concentration set-point or above aparticular percentage of the residual chloramine concentrationset-point, at which point the programming instructions will cause thecontroller 40 to stop the supply of chlorine and ammonia into the bodyof water 12. The method step of stopping the addition of chlorine andammonia into the body of water 12 can be controlled, for example, withprogramming algorithm III or with programming algorithm VII.

Alternatively, if the residual chloramine concentration in thesubsequent water sample is determined to be at or above the set rate ofchange in chloramine concentration but below the residual chloramineconcentration set-point, the programming instructions will cause thecontroller 40 to continue to automatically engage (or control) a supplyof chlorine to add chlorine only to the body of water 12. The methodstep of continually adding chlorine after further analysis can becontrolled, for example, with programming algorithm IV.

Further, if the residual chloramine concentration in the subsequentwater sample is determined to be at or above the residual chloramineconcentration set-point or above a particular percentage of the residualchloramine concentration set-point, the programming instructions willcause the controller 40 to stop the supply of chlorine into the body ofwater 12. The method step of stopping the addition of chlorine into thebody of water 12 can be controlled, for example, with programmingalgorithm V or with programming algorithm VI.

As indicated, any of the previously described method steps, orcombination of steps, can be used to establish, reestablish, andmaintain a desired residual chloramine level within the body of water12. In one preferred and non-limiting embodiment or aspect, at least oneof the previously described method steps, or combination of steps, areused to establish or reestablish a desired residual chloramineconcentration set-point. After the desired residual chloramineconcentration set-point is established or reestablished to complete afirst treatment cycle, a different algorithm can be used to reestablishthe desired residual chloramine concentration in subsequent treatmentcycles.

In one preferred and non-limiting embodiment or aspect, after a firsttreatment cycle is completed, the controller 40 is programmed to onlyengage (or control) a supply of chlorine and a supply of ammonia to addboth chlorine and ammonia to the body of water 12 in order toreestablish the desired residual chloramine concentration set-point.Thus, in such embodiments, chlorine alone is not added to the body ofwater 12 in a second treatment cycle. For example, after a firsttreatment cycle is completed, the programming instructions of thecomputer-readable storage mediums can be configured to cause thecontroller 40 to automatically add both chlorine and ammonia to the bodyof water 12 when the residual chloramine concentration in a water sampleis determined to be below the residual chloramine concentrationset-point.

In some preferred and non-limiting embodiments or aspects, thepreviously described method step of adding ammonia and chlorine into thebody of water 12 in a second treatment cycle is controlled by thefollowing algorithm IX: y′<x′=add chlorine and ammonia, where “y′” isthe residual chloramine concentration determined in a water sample ofthe second treatment cycle and “x′” is the residual chloramineconcentration set-point. Thus, the programming instructions can includealgorithm IX for use in a second treatment cycle that, when satisfied,will cause the controller 40 to automatically engage (or control) asupply of chlorine and a supply of ammonia to add both chlorine andammonia to the body of water 12.

The method can also use a chloramine concentration percentage of theresidual chloramine concentration set-point to determine when to addboth chlorine and ammonia to the body of water 12 in a second treatmentcycle. The chloramine concentration percentage can include, for example,a percentage selected within a range of 99% to 80% of the residualchloramine concentration set-point.

In some preferred and non-limiting embodiments or aspects, thepreviously described method step of adding chlorine and ammonia into thebody of water 12 in a second treatment cycle based on a chloramineconcentration percentage is controlled by the following algorithm X:y′<[(a′)(x′)]=add chlorine and ammonia, where “y′” is the residualchloramine concentration determined in the first water sample of thesecond treatment cycle, “a” is a percentage selected within a range of99% to 80%, and “x′” is the residual chloramine concentration set-point.Thus, the programming instructions can include algorithm X for use in asecond treatment cycle that, when satisfied, will cause the controller40 to automatically engage (or control) a supply of chlorine and asupply of ammonia to add both chlorine and ammonia to the body of water12.

Chlorine and ammonia are added to the body of water 12 until asubsequently obtained water sample is determined to be at or above theresidual chloramine concentration set-point or above a particularpercentage of the residual chloramine concentration set-point, at whichpoint the programming instructions will cause the controller 40 to stopthe supply of chlorine and ammonia into the body of water 12. The methodstep of stopping the addition of chlorine and ammonia into the body ofwater 12 can be controlled, for example, with programming algorithm IIIor with programming algorithm VII.

After reestablishing the target residual chloramine concentrationset-point in the second treatment cycle, the programming instructionswill cause the controller 40 to revert back to the original algorithm orcause the controller 40 to continue to use the modified algorithm. It isappreciated that the controller 40 can be programmed to alternatebetween different algorithms for any desired number of treatment cycles.For example, in a first treatment cycle, the controller 40 can beprogrammed to supply chlorine alone in a first step and, optionally,both chlorine and ammonia in a second step in order to establish theresidual chloramine concentration set-point. Then, after a firsttreatment cycle is completed, the controller 40 can be programmed tosupply both chlorine and ammonia only in order to reestablish theresidual chloramine concentration set-point in the next three treatmentcycles. Finally, to reestablish the residual chloramine concentrationset-point in a fifth treatment cycle, the controller 40 can beprogrammed to use the original algorithm and supply chlorine alone in afirst step and, optionally, both chlorine and ammonia in a second step.

The feed rate of chlorine and/or ammonia in any of the previouslydescribed steps can be determined from the reservoir 14 water volume anddwell time. As used herein, “dwell time” refers to the rate at whichwater volume changes in the reservoir 14. The feed rate of the chlorineand ammonia can also be controlled by the speed at which the meteringpumps distribute the chlorine and ammonia into the body of water 12. Forexample, the metering pumps can distribute chlorine and ammonia at amaximum speed rate. The metering pumps can also be reduced to half(i.e., 50%) of the maximum speed rate to adjust the feed rate ofchlorine and ammonia.

Further, when adding both chlorine and ammonia into the body of water12, the controller 40 typically adds each chemical at an amount thatprovides a particular weight ratio of chlorine to ammonia. In certainpreferred and non-limiting embodiments or aspects, the chlorine andammonia are added to the body of water 12 to provide a weight ratio ofchlorine to ammonia of 5:1.

The method of automatically controlling chloramine concentrationdescribed herein allows for a desired amount of chloramine in a body ofwater 12 to be effectively maintained without directly measuring orinitially adding free ammonia. The system and method can also be used torespond to an adjustment, such as an increase, in the target chloramineconcentration.

FIGS. 6 and 7 show the residual chloramine concentration and rate ofchange in chloramine concentration in a water storage reservoir thatutilized the treatment delivery system 10 and the method ofautomatically controlling chloramine concentration by adding a source ofchlorine only. The treatment delivery system 10 was programmed to addchlorine when the residual chloramine concentration was below theresidual chloramine set-point. Further, while adding chlorine, thetreatment delivery system 10 was also programmed to add chlorine andammonia when two consecutive determinations in the rate of change inresidual chloramine concentration obtained over a specified period oftime were below the set rate of change in chloramine concentration of0.02 mg/L/hour.

As shown in FIG. 6, the system was turned on around 8:15 AM andhypochlorite was added to the body of water 12 after determining that awater sample had a residual chloramine concentration below the residualchloramine set-point. After adding the chlorine, the residual chloramineconcentration in additional water samples were determined and the rateof change in chloramine concentration was calculated throughout theprocess. Because two consecutive determinations in the rate of change inresidual chloramine concentration obtained over a specified period oftime were not below the set rate of change in chloramine concentration,the supply of ammonia was never engaged. Moreover, the chloramineset-point was reached around 10:00 AM and the supply of chlorine intothe body of water 12 was stopped.

As shown in FIG. 7, the system was turned on around after 9:00 AM andhypochlorite was added to the body of water 12 after determining that awater sample had a residual chloramine concentration below the residualchloramine set-point. After adding the chlorine, the residual chloramineconcentration in additional water samples were determined and the rateof change in chloramine concentration was calculated throughout theprocess. Because two consecutive determinations in the rate of change inresidual chloramine concentration obtained over a specified period oftime were below the set rate of change in chloramine concentration, thesupply of ammonia was engaged such that both chlorine and ammonia wereadded to the body of water 12. Moreover, the chloramine set-point wasreached around 11:30 AM and the supply of chlorine and ammonia into thebody of water 12 were stopped.

Whereas particular embodiments of this invention have been describedabove for purposes of illustration, it will be evident to those skilledin the art that numerous variations of the details of the presentinvention may be made without departing from the invention as defined inthe appended claims.

The invention claimed is:
 1. A method of automatically controllingchloramine concentration in a body of water contained in a reservoir,the method comprising: a) determining residual chloramine concentrationin a water sample obtained from the body of water; b) automaticallyengaging a supply of chlorine to add chlorine to the body of water when:i) the residual chloramine concentration in the water sample isdetermined to be below a predetermined residual chloramine concentrationset-point; or ii) the residual chloramine concentration in the watersample is determined to be below a chloramine concentration percentageof a predetermined residual chloramine concentration set-point; c)determining residual chloramine concentration in one or more additionalwater samples obtained from the body of water after step b); d)determining the rate of change in chloramine concentration based on theresidual chloramine concentration obtained from at least two watersamples of step c) or based on the residual chloramine concentrationobtained from a water sample in step c) and the water sample in step a)if the residual chloramine concentration in the additional water samplesis below the predetermined residual chloramine concentration set-pointor the chloramine concentration percentage of a predetermined residualchloramine concentration set-point; and e) if the rate of change inchloramine concentration is below a set rate of change in chloramineconcentration (i) automatically engaging a supply of ammonia and thesupply of chlorine to add both ammonia and chlorine to the body ofwater, or (ii) stopping the supply of chlorine after step (d).
 2. Themethod of claim 1, wherein the supply of chlorine is added to the bodyof water in step b) when (i) the residual chloramine concentration inthe water sample of step a) is determined to be below the predeterminedresidual chloramine concentration set-point.
 3. The method of claim 1,wherein the supply of chlorine is added to the body of water in step b)when (ii) the residual chloramine concentration in the water sample ofstep a) is determined to be below the chloramine concentrationpercentage of the predetermined residual chloramine concentrationset-point.
 4. The method of claim 1, wherein the rate of change inchloramine concentration is determined by comparing the chloramineconcentration in at least one water sample of step a) or step c) withthe chloramine concentration in a subsequent water sample of step c)obtained after a set period of time.
 5. The method of claim 1, whereinthe ammonia and chlorine are both added to the body of water in step e)when two consecutive determinations in the rate of change in chloramineconcentration are below the set rate of change in chloramineconcentration.
 6. The method of claim 1, wherein, if the rate of changein chloramine concentration is determined to be at or above the set rateof change in chloramine concentration, the addition of chlorine only tothe body of water is maintained.
 7. The method of claim 1, wherein, ifthe residual chloramine concentration in a water sample is determined tobe at or above the predetermined residual chloramine concentrationset-point in step c), the supply of chlorine to the body of water isstopped.
 8. The method of claim 1, wherein the supply of chlorine andthe supply of ammonia are added to the body of water during step e)until a subsequently obtained water sample is determined to be at orabove the predetermined residual chloramine concentration set-point. 9.The method of claim 1, wherein the chloramine concentration percentageis a percentage selected within a range of about 99% to about 80% of thepredetermined residual chloramine concentration set-point.
 10. Themethod of claim 1, wherein a feed rate of at least one of the chlorineand ammonia are determined by reservoir water volume and dwell time. 11.The method of claim 1, wherein, if it is determined that the body ofwater has a residual chloramine concentration at or above thepredetermined residual chloramine concentration set-point after step b)or step e), the method further comprises: f) determining residualchloramine concentration in a subsequent water sample obtained from thebody of water; and g) automatically engaging the supply of ammonia andthe supply of chlorine to add both ammonia and chlorine to the body ofwater if: i) the residual chloramine concentration in the subsequentwater sample is determined to be below the predetermined residualchloramine concentration set-point; or ii) the residual chloramineconcentration in the subsequent water sample is determined to be belowthe chloramine concentration percentage of the predetermined residualchloramine concentration set-point.
 12. The method of claim 1, whereindetermining the residual chloramine concentration in the water samplescomprises measuring a total chlorine concentration in the water samples.13. The method of claim 1, wherein the chlorine and ammonia are bothautomatically added to the body of water to provide a weight ratio ofchlorine to ammonia of 5:1.
 14. The method of claim 1, wherein thechlorine and, optionally, the ammonia, are added to the body of water bya chemical dosing assembly that comprises chemical treatment flow tubesand a water motive tube, and wherein the chlorine and, optionally, theammonia, are added to the body of water by the chemical treatment flowtubes in an area above the water motive tube to form a high energymixing zone.
 15. The method of claim 1, further comprising re-startingthe method at step a) after a predetermined period of time when thesupply of chlorine is stopped after step d).
 16. A treatment deliverysystem for automatically controlling chloramine concentration in a bodyof water contained in a reservoir comprising: a chemical dosing assemblyat least partially submerged in the body of water; a water samplingassembly configured to extract water samples from the body of water atdifferent points in time; an analyzer in fluid communication with thewater sampling assembly and configured to determine residual chloramineconcentration in the water samples; a controller in operablecommunication with the analyzer; and one or more computer-readablestorage mediums in operable communication with the controller andcontaining programming instructions that, when executed, cause thecontroller to: a) determine residual chloramine concentration in a watersample obtained from the body of water; b) automatically engage a supplyof chlorine to add chlorine to the body of water when: i) the residualchloramine concentration in the water sample is determined to be below apredetermined residual chloramine concentration set-point; or ii) theresidual chloramine concentration in the water sample is determined tobe below a chloramine concentration percentage of a predeterminedresidual chloramine concentration set-point; c) determine residualchloramine concentration in one or more additional water samplesobtained from the body of water after step b); d) determine the rate ofchange in chloramine concentration based on the residual chloramineconcentration obtained from at least two water samples of step c) orbased on the residual chloramine concentration obtained from a watersample in step c) and the water sample in step a) if the residualchloramine concentration in the additional water samples is below thepredetermined residual chloramine concentration set-point or thechloramine concentration percentage of a predetermined residualchloramine concentration set-point; and e) if the rate of change inchloramine concentration is below a set rate of change in chloramineconcentration (i) automatically engage a supply of ammonia and thesupply of chlorine to add both ammonia and chlorine to the body ofwater, or (ii) stop the supply of chlorine after step (d).
 17. Thesystem of claim 16, wherein the water sampling assembly is a componentof the chemical dosing assembly.
 18. The system of claim 16, wherein theanalyzer comprises a total chlorine analyzer.
 19. The system of claim17, wherein the chemical dosing assembly further comprises a watermotive tube positioned below a release point of at least one chemicaltreatment flow tube.
 20. The system of claim 19, wherein the chemicaldosing assembly further comprises a second chemical treatment flow tubeand wherein the water motive tube is positioned below a release point ofthe second chemical treatment flow tube.
 21. The system of claim 20,wherein the first and second chemical treatment flow tubes areconfigured to deliver the chlorine and, optionally, the ammonia, to anarea above a release point of the water motive tube to form a highenergy mixing zone.
 22. The system of claim 16, further comprising ahypochlorite storage tank, an ammonia storage tank, or both ahypochlorite storage tank and an ammonia storage tank.
 23. The system ofclaim 16, further comprising a hypochlorite generation system.
 24. Thesystem of claim 16, wherein the controller is programmed to providechlorine and ammonia at a weight ratio of chlorine to ammonia of 5:1.